Semiconductor storage device

ABSTRACT

According to one embodiment, a semiconductor storage device includes a cell array including resistance change elements formed above a semiconductor substrate; first cell transistors formed on the semiconductor substrate and provided in association with the resistance change elements; first gate electrodes included in the first cell transistor and extending in a first direction; a first bit lines electrically connected to the resistance change elements respectively and extending in a second direction perpendicular to the first direction; a second bit lines electrically connected to one end of a current path of the first cell transistors respectively and extending in the second direction; and first active areas in which the first cell transistors are formed, and which extend in a direction crossing the first direction at a first angle.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/876,491, filed Sep. 11, 2013, the entire contents of which areincorporated herein by reference.

FIELD

Embodiments described herein relate generally to a semiconductor storagedevice.

BACKGROUND

There is known a magnetic random access memory (MRAM) as one ofresistance change type memories. Writing methods of MRAMs include amagnetic field writing method and a spin transfer writing method. Ofthese methods, the spin transfer method is advantageous in increasing anintegration density, reducing power consumption and enhancingcapabilities, since this method has such a characteristic that a spintransfer current that is necessary for magnetization reversal decreasesas the size of a magnetic body becomes smaller.

An MTJ (Magnetic Tunnel Junction) element of the spin transfer writingmethod has a multilayer structure which is composed of two ferromagneticlayers and a nonmagnetic barrier layer (insulation thin film) interposedtherebetween, and digital data is stored by a change in magneticresistance due to a spin polarization tunnel effect. The MTJ element maytake a low resistance state and a high resistance state by amagnetization orientation of the two ferromagnetic layers. When themagnetization orientation (spin direction) of the two ferromagneticlayers is in a parallel state (P (Parallel) state), the MTJ element isin the low resistance state. When the magnetization orientation of thetwo ferromagnetic layers is in an antiparallel state (AP (AntiParallel)state), the MTJ element is in the high resistance state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a structure of a semiconductorstorage device according to a first embodiment.

FIG. 2 is a view illustrating a write operation of a memory cellaccording to the first embodiment.

FIG. 3 illustrates an example of a layout of a cell array and aperipheral circuit thereof according to the first embodiment.

FIG. 4 is a block diagram illustrating a relationship between the cellarray and a bit line and source line controller according to the firstembodiment.

FIG. 5 is a circuit diagram illustrating the relationship between thecell array and the bit line and source line controller according to thefirst embodiment.

FIG. 6 is a circuit diagram illustrating a relationship between the cellarray and a bit line controller according to the first embodiment.

FIG. 7 is a circuit diagram illustrating a relationship between the cellarray and a source line controller according to the first embodiment.

FIG. 8 is a layout illustrating the relationship between the cell arrayand the bit line controller according to the first embodiment.

FIG. 9 is a cross-sectional view taken along line A-A in FIG. 8.

FIG. 10 is a cross-sectional view taken along line B-B in FIG. 8.

FIG. 11 is a layout illustrating the relationship between the cell arrayand the source line controller according to the first embodiment.

FIG. 12 is a flowchart which schematically illustrates a basicmanufacturing method of the semiconductor storage device according tothe first embodiment.

FIG. 13 is a block diagram which schematically illustrates a structureof a subhole.

FIG. 14A is a circuit diagram illustrating an inverter of a columnselect circuit driver.

FIG. 14B is a circuit diagram illustrating an SWD driver of the columnselect circuit driver.

FIG. 14C is a circuit diagram of an SWD driver.

FIG. 14D is a circuit diagram of a BL/SL reset driver.

DETAILED DESCRIPTION

Also in a resistance change type memory which can realize fine cells asdescribed in the “BACKGROUND”, an adequate cell capability cannot bederived by simply enlarging a memory cell array area, owing to anincrease in resistance of a wiring layer by microfabrication. It is thusnecessary to divide the cell array, thereby decreasing the influence ofthe increase in wiring resistance. To divide the cell array means toincrease the number of core circuits around the cell array, leadingsimply to an increase in chip size. In the present application, the areaof the core circuit is reduced by using a miniaturization technique ofmemory cells for the core circuit around the memory cell array, therebyrealizing a resistance change type memory device which has an improvedcapability and margin, while suppressing an increase in chip size.

In general, according to one embodiment, a semiconductor storage deviceincludes a cell array including a plurality of resistance changeelements formed above a semiconductor substrate, a plurality of firstcell transistors formed on the semiconductor substrate and provided inassociation with the resistance change elements, a plurality of firstgate electrodes included in the first cell transistor and extending in afirst direction, a first bit line electrically connected to theresistance change element and extending in a second directionperpendicular to the first direction, a second bit line electricallyconnected to one end of a current path of the first cell transistor andextending in the second direction, and a plurality of first active areasin which the first cell transistors are formed, and which extend in adirection crossing the first direction at a first angle. Thesemiconductor storage device also includes a bit line controllerincluding a plurality of second cell transistors formed on thesemiconductor substrate and each having a current path with one endelectrically connected to the first bit line or the second bit line, aplurality of second gate electrodes included in the second celltransistors and extending in the first direction, and a plurality ofsecond active areas in which the second cell transistors are formed, andwhich extend in a direction crossing the first direction at a secondangle.

Hereinafter, embodiments, which have been constructed, will be describedwith reference to the accompanying drawings. In the description below,structural elements having substantially the same functions andstructures are denoted by like reference signs, and an overlappingdescription is given only where necessary. The “alphabet” or “hyphen &numeral” after a numeral, which constitutes a reference sign, and the“numeral” or “hyphen & numeral” after a symbol, which constitutes areference sign, are used in order to distinguish elements which arereferred to by reference signs including the same numeral and have thesame structure. When it is not necessary to distinguish elements whichare indicated by reference signs including the same numeral, theseelements are referred to by a reference sign including only a numeral ora symbol. For example, when it is not necessary to distinguish elementswith reference signs 1 a and 1 b, these elements are comprehensivelyreferred to by a reference sign 1. In addition, for example, when it isnot necessary to distinguish elements with reference signs WL1 and WL2,these elements are comprehensively referred to by a reference sign WL.

It should be noted that the drawings are schematic ones, and therelationship between a thickness and a planar dimension, the ratio inthickness between layers, etc. are different from real ones. Thus,concrete thicknesses and dimensions should be judged in consideration ofdescriptions below. Needless to say, the drawings include parts withmutually different relations or ratios of dimensions. Besides,embodiments to be described below illustrate, by way of example, devicesor methods for embodying technical concepts of the embodiments, and thetechnical concepts of the embodiments do not specifically restrict thematerial, shape, structure, arrangement, etc. of structural componentsto those described below. Various changes may be made in the technicalconcepts of the embodiments within the scope of the claims.

First Embodiment Structure of a Semiconductor Storage Device Accordingto a First Embodiment

To begin with, referring to FIG. 1, a basic structure of a semiconductorstorage device according to a first embodiment is schematicallydescribed. FIG. 1 is a block diagram illustrating the structure of thesemiconductor storage device according to the first embodiment.

The semiconductor storage device 1 of the first embodiment includes amemory cell array (also referred to simply as “cell array”) 11, acontroller 12, a DQ circuit 13, an address command circuit 14, a rowdecoder 15, a subhole 16, a bit line and source line controller 17, asense amplifier/write driver 18, a word line driver 20, and an internalvoltage generator 21. The subhole 16 generates a control signal of theword line driver 20 and a control signal of the bit line and source linecontroller 14, in association with each memory cell array 11.

The cell array 11 is an MRAM, in which a plurality of memory cells MCare arranged two-dimensionally in a matrix. Each memory cell MC includesan MTJ element 22 (not shown) and a cell transistor 23 (not shown). TheMTJ element 22 is a magnetic tunnel junction element which stores databy a change in resistance state, and can rewrite data by an electriccurrent. The cell transistor 23 is provided in association with the MTJelement 22, and is configured to be rendered conducive when a current iscaused to flow in the associated MTJ element 22.

A plurality of word lines WL are arranged in a row direction and aplurality of bit lines BL are arranged in a column direction such thatthe word lines WL and bit lines BL cross each other. Two neighboring bitlines BL constitute a pair, and the memory cell MC is provided inassociation with an intersection between the word line WL and the bitline pair (in this embodiment, for convenience′ sake, referred to as abit line BL and a source line SL). The MTJ element 22 and celltransistor 23 of each memory cell MC are connected in series between thebit line pair (e.g. between BL and SL). In addition, the gate of thecell transistor 23 is connected to the word line WL.

Various external control signals, for instance, a chip select signal CS,a clock signal CK and a clock enable signal CKE, are input to thecontroller 12. The controller 12 controls the address command circuit14, and discriminates an address and a command.

A command address signal CAi is input to the address command circuit 14.The address command circuit 14 transfers the command address signal CAito the row decoder 15 and subhole 16.

The row decoders 15 are disposed on both sides in the word linedirection of the memory cell array 11, and decode an address of thecommand address signal CAi which has been supplied from the addresscommand circuit 14.

The subhole 16 recognizes, based on an external control signal, acommand or an address by the command address signal CAi, and controlsthe word line driver 20 and the bit line and source line controller 17.

The bit line and source line controller 17 are disposed on both sides inthe bit line direction of the memory cell array 11, and control the bitline BL and source line SL, based on a control signal from the subhole16.

The sense amplifier/write driver 18 is disposed in a bit line directionof the memory cell array 11. The sense amplifier is connected to the bitline EL, and reads out data stored in the memory cell by sensing acurrent flowing in the memory cell MC which is connected to the selectedword line WL. The write driver is connected to the bit line BL, andwrites data by causing a current to flow in the memory cell MC which isconnected to the selected word line WL.

The transmission/reception of data between the sense amplifier/writedriver 18 and an external input/output terminal DQ is executed via adata bus 19 and the DQ circuit 13.

The word line drivers 20 are disposed on both sides in the word linedirection of the memory cell array 11 and connected to the word lines,and are configured to apply a voltage to the selected word line WL at atime of data read or data write. More specifically, the word line driver20 is configured to apply a voltage to the selected word line WL, inaccordance with a row address decoded by the row decoder 15.

The internal voltage generator 21 is provided in order to generate aninternal voltage (e.g. a voltage boosted by a power supply voltage)which is necessary for operations in the semiconductor storage device 1.This internal voltage generator 21, too, is controlled by the controller12, and executes a boost operation and generates a necessary voltage.

<Write Operation of Memory Cell MC>

Next, referring to FIG. 2, a write operation of the memory cell MCaccording to the first embodiment is schematically described. FIG. 2 isa view illustrating the write operation of the memory cell MC accordingto the first embodiment.

As illustrated in FIG. 2, one end of an MTJ element 22 of the memorycell MC according to the first embodiment is connected to the bit lineBL, and the other end of the MTJ element 22 is connected to one end of acurrent path of a cell transistor 23. The other end of the current pathof the cell transistor 23 is connected to the source line SL. The MTJelement 22, which makes use of a TMR (tunneling magnetoresistive)effect, has a multilayer structure which is composed of twoferromagnetic layers F and P and a nonmagnetic (tunnel insulation film)B interposed therebetween, and stores digital data by a change inmagnetic resistance by a spin polarization tunnel effect. The MTJelement 22 may take a low resistance state and a high resistance stateby a magnetization orientation of the two ferromagnetic layers F, P. Forexample, if the low resistance state is defined as data “0” and the highresistance state is defined as data “1”, 1 bit data can be stored in theMTJ element 22. Needless to say, the low resistance state may be definedas data “1” and the high resistance state may be defined as data “0”.

For example, the MTJ element 22 is configured such that a fixed layer(pin layer) P, a tunnel barrier layer B and a recording layer (freelayer) F are successively stacked. The pin layer P and free layer F areformed of a ferromagnetic material, and the tunnel barrier layer B isformed of an insulation film (e.g. Al₂O₃, MgO). The pin layer P is alayer with a fixed direction of magnetization orientation. The freelayer F has a variable direction of magnetization orientation, and datais stored by the direction of magnetization.

If an electric current is caused to flow in a direction of arrow A1 at atime of write, the magnetization direction of the free layer F is set inan antiparallel state (AP state), relative to the magnetizationdirection of the pin layer P, and a high resistance state (data “1”) isset. If an electric current is caused to flow in a direction of arrow A2at a time of write, the magnetization directions of the pin layer P andfree layer F are set in a parallel state (P state), and a low resistancestate (data “0”) is set. In this manner, in the MTJ element, differentdata can be written in accordance with the direction of flow of anelectric current.

<Structure of Cell Arrays According to the First Embodiment andPeripheral Circuits Thereof>

Next, referring to FIG. 3 to FIG. 11, a layout of cell arrays andperipheral circuits thereof according to the first embodiment isschematically described. FIG. 3 illustrates an example of the layout ofcell arrays and peripheral circuits thereof according to the firstembodiment. FIG. 4 is a block diagram illustrating a relationshipbetween the cell array and the bit line and source line controlleraccording to the first embodiment. FIG. 5 is a circuit diagramillustrating the relationship between the cell array and the bit lineand source line controller according to the first embodiment. FIG. 6 isa circuit diagram illustrating a relationship between the cell array anda bit line controller according to the first embodiment. FIG. 7 is acircuit diagram illustrating a relationship between the cell array and asource line controller according to the first embodiment. FIG. 8 is alayout illustrating the relationship between the cell array and the bitline controller according to the first embodiment. FIG. 9 is across-sectional view taken along line A-A in FIG. 8. FIG. 10 is across-sectional view taken along line B-B in FIG. 8. FIG. 11 is a layoutillustrating the relationship between the cell array and the source linecontroller according to the first embodiment.

As illustrated in FIG. 3, bit line and source line controllers 17 areprovided along both ends along an X direction of each cell array 11. Twobit line and source line controllers 17, which are juxtaposed with eachcell array 11, are used for controlling the cell array 11.

In addition, as shown in FIG. 3, word line drivers 20 are provided alongboth ends along a Y direction of each cell array 11. Two word linedrivers 20, which are juxtaposed with each cell array 11, are used forcontrolling the cell array 11.

The subhole 16 is provided at an intersection between a column in whichword line drivers 20 are arranged and a row in which bit line and sourceline controllers 17 are arranged.

As illustrated in FIG. 4, the bit line and source line controller 17includes a bit line select circuit CG_BL and a source line selectcircuit CG_SL.

The bit line select circuit CG_BL includes switch transistors 24-1 to24-n (n is an integer of 1 or more), and selectively connects a globalbit line GBL of the sense amplifier/write driver 18 to an n-number oflocal bit lines LBL1 to LBLn.

In addition, the source line select circuit CG_SL includes switchtransistors 26-1 to 26-n, and selectively connects a global source lineGSL of the sense amplifier/write driver 18 to an n-number of localsource lines LSL1 to LSLn.

In the cell array 11, a word line, to which an output of the word linedriver 20 is connected and which corresponds to a selected cell, isactivated.

The bit line select circuit CG_BL receives an output signal from thesubhole 16. In the bit line select circuit CG_BL, based on this outputsignal, a switch transistor 24-i corresponding to a selected local bitline BLi (i is an integer of 1 or more), among an n-number of switchtransistors 24-1 to 24-n, is turned on. Then, the selected local bitline LBLi is connected to the global bit line GBL, and is connected tothe sense amplifier/write driver 18.

Similarly, the source line select circuit CG_SL receives an outputsignal from the subhole 16. In the source line select circuit CG_SL,based on this output signal, a switch transistor 26-i corresponding to aselected local source line LSLi, among an n-number of switch transistors26-1 to 26-n, is turned on. Then, the selected local source line LSLi isconnected to the global source line GSL, and is connected to the senseamplifier/write driver 18.

As illustrated in FIG. 5, the bit line select circuit CG_BL includes acolumn select circuit 17E1 and a bit line discharge circuit 17B2.

The column select circuit 17B1 includes cell transistors 24-1 to 24-nfunctioning as switch transistors 24-1 to 24-n. An output signal fromthe subhole 16 is input to the gate electrode of each of the celltransistors 24-1 to 24-n, and the global bit line GBL is connected toone end of a current path of each of the cell transistors 24-1 to 24-n.In addition, the current paths of the respective cell transistors 24-1to 24-n are connected to the associated local bit lines LBL1 to LBLn.

The bit line discharge circuit 17B2 includes reset transistors 25between the cell transistors 24-1 to 24-n and the local bit lines LBLnto LBLn. Based on a reset signal from the subhole 16, the bit linedischarge circuit 17B2 connects the local bit line to a groundpotential. To be more specific, an output signal from the subhole 16 isinput to the gate of the reset transistor 25. In addition, any one ofthe local bit lines LBL1 to LBLn is connected to one end of a currentpath of the reset transistor 25, and the other end of the current pathis connected to a ground potential.

Besides, as illustrated in FIG. 5, the source line select circuit CG_SLincludes a column select circuit 17S1 and a source line dischargecircuit 17S2.

The column select circuit 17S1 includes cell transistors 26-1 to 26-nfunctioning as switch transistors 26-1 to 26-n. An output signal fromthe subhole 16 is input to the gate electrode of each of the celltransistors 26-1 to 26-n, and the global source line GSL is connected toone end of a current path of each of the cell transistors 26-1 to 26-n.In addition, the current paths of the respective cell transistors 26-1to 26-n are connected to the associated local source lines LSL1 to LSLn.

The source line discharge circuit 17S2 includes reset transistors 27between the cell transistors 26-1 to 26-n and the local source linesLSL1 to LSLn. Based on a reset signal from the subhole 16, the sourceline discharge circuit 17S2 connects the local source line to a groundpotential. To be more specific, an output signal from the subhole 16 isinput to the gate of the reset transistor 27. In addition, any one ofthe local source lines LSL1 to LSLn is connected to one end of a currentpath of the reset transistor 27, and the other end of the current pathis connected to a ground potential.

Next, referring to FIG. 6, the circuit structure of the column selectcircuit 17B1 is described in greater detail. In FIG. 6, for the purposeof simple description, only four local bit lines LBL and four localsource lines LSL are shown, and only eight memory cells MC in the cellarray 11 are shown.

As illustrated in FIG. 6, a memory cell MC1 includes an MTJ element 22-1which has one end connected to a local bit line LBL1, and a transistor23-1 which has a current path with one end connected to a local sourceline LSL1 and the other end connected to the other end of the MTJelement 22-1, and has a gate electrode receiving an input from a wordline WL1. In addition, a memory cell MC2 includes an MTJ element 22-2which has one end connected to the local bit line LBL1, and a transistor23-2 which has a current path with one end connected to the local sourceline LSL1 and the other end connected to the other end of the MTJelement 22-2, and has a gate electrode receiving an input from a wordline WL2. A memory cell MC3 includes an MTJ element 22-3 which has oneend connected to a local bit line LBL2, and a transistor 23-3 which hasa current path with one end connected to a local source line LSL2 andthe other end connected to the other end of the MTJ element 22-3, andhas a gate electrode receiving an input from the word line WL1. A memorycell MC4 includes an MTJ element 22-4 which has one end connected to thelocal bit line LBL2, and a transistor 23-4 which has a current path withone end connected to the local source line LSL2 and the other endconnected to the other end of the MTJ element 22-4, and has a gateelectrode receiving an input from the word line WL2. Similarly, memorycells MC5 and MC6 are connected to a local bit line LBL3 and a localsource line LSL3, and memory cells MC7 and MC8 are connected to a localbit line LBL4 and a local source line LSL4. In addition, the memorycells MC5 and MC7 are connected to the word line WL1, and the memorycells MC6 and MC8 are connected to the word line WL2. The local bitlines LBL1 to LBL4 are connected wiring lines M1 via via-contacts V1,respectively. Incidentally, as shown in FIG. 6, the local source lineLSL is the wiring line M1. However, by a fabrication step called “M1cut”which will be described later, the local source line LSL (see ellipticparts indicated by broken lines in the Figure) is physically cut, sothat no short-circuit may occur between the local bit line LBL and localsource line LSL by the local bit line LBL being connected to M1 via thevia-contact V1.

In addition, as illustrated in FIG. 6, the bit line discharge circuit17B2 includes, for example, reset transistors 25-1 to 25-4. The resettransistor 25-1 has a current path with one end connected to M1 a andthe other end connected to a ground potential, and has a gate electrodeto which a reset signal RESET1 b is input. The reset transistor 25-2 hasa current path with one end connected to M1 b and the other endconnected to a ground potential, and has a gate electrode to which areset signal RESET2 b is input. The reset transistor 25-3 has a currentpath with one end connected to M1 c and the other end connected to aground potential, and has a gate electrode to which the reset signalRESET1 b is input. The reset transistor 25-4 has a current path with oneend connected to M1 d and the other end connected to a ground potential,and has a gate electrode to which the reset signal RESET2 b is input.

Besides, as illustrated in FIG. 6, the column select circuit 17B1includes switch transistors 24-1 to 24-4. The switch transistor 24-1includes switch transistors 24-1 a, 24-1 b, 24-1 c and 24-1 d, each ofwhich has a current path with one end connected to the wiring line M1 avia a wiring line LI-1 and the other end connected to a global bit lineGBL1 (M1) via a wiring line LI-2, and has a gate electrode to which acontrol signal CGE1 b is input.

In addition, the switch transistor 24-2 includes switch transistors 24-2a, 24-2 b, 24-2 c and 24-2 d, each of which has a current path with oneend connected to the wiring line M1 b via a wiring line LI-3 and theother end connected to the global bit line GBL1 (M1) via a wiring lineLI-4, and has a gate electrode to which a control signal CGE2 b isinput.

The switch transistor 24-3 includes switch transistors 24-3 a, 24-3 b,24-3 c and 24-3 d, each of which has a current path with one endconnected to the wiring line M1 c via a wiring line LI-5 and the otherend connected to the global bit line GBL1 (M1) via a wiring line LI-6,and has a gate electrode to which a control signal CGE3 b is input.

The switch transistor 24-4 includes switch transistors 24-4 a, 24-4 b,24-4 c and 24-4 d, each of which has a current path with one endconnected to the wiring line M1 d via a wiring line LI-7 and the otherend connected to the global bit line GBL1 (M1) via a wiring line LI-8,and has a gate electrode to which a control signal CGE4 b is input.

In the meantime, the wiring line Mia and global bit line GBL1 (M1) arephysically cut by the above-described M1cut step. Similarly, the wiringlines M1 b, M1 c and M1 d and the global bit line GBL1 (M1) arephysically cut by the above-described M1cut step.

In addition, the global bit line GBL1 (M1) is connected to a global bitline GBL1 (M2) via a via-contact V1.

In FIG. 6, in each of the switch transistors 24-1 to 24-4, fourtransistors are operated as one transistor. Alternatively, in each ofthe switch transistors 24-1 to 24-4, more than four transistors, forinstance, 8 transistors or 16 transistors, may be operated as onetransistor.

The wiring lines designated by “M1” are formed by the same fabricationstep, the wiring lines designated by “M2” are formed by the samefabrication step, and the wiring lines designated by “L1” are formed bythe same fabrication step. In addition, the plugs designated by “V1” areformed by the same fabrication step. Besides, the transistors 23 of thecell array 11, the transistors 25, and the switch transistors 24-1 a,24-1 b, 24-1 c, 24-1 d, 24-2 a, 24-2 b, 24-2 c, 24-2 d, 24-3 a, 24-3 b,24-3 c, 24-3 d, 24-4 a, 24-4 b, 24-4 c, and 24-4 d are cell transistorsof the same size.

Next, referring to FIG. 7, the circuit structure of the column selectcircuit 17S1 is described in greater detail. In FIG. 7, like FIG. 6, forthe purpose of simple description, only four local bit lines LBL andfour local source lines LSL are shown, and only eight memory cells MC inthe cell array 11 are shown. Since the structure of the cell array 11 isthe same as that described with reference to FIG. 6, a descriptionthereof is omitted here.

As illustrated in FIG. 7, the source line discharge circuit 17S2includes, for example, reset transistors 27-1 to 27-4. The resettransistor 27-1 has a current path with one end connected to M1 a andthe other end connected to a ground potential, and has a gate electrodeto which a reset signal RESET1 s is input. The reset transistor 27-2 hasa current path with one end connected to M1 b and the other endconnected to a ground potential, and has a gate electrode to which areset signal RESET2 s is input. The reset transistor 27-3 has a currentpath with one end connected to M1 c and the other end connected to aground potential, and has a gate electrode to which the reset signalRESET1 s is input. The reset transistor 27-4 has a current path with oneend connected to M1 d and the other end connected to a ground potential,and has a gate electrode to which the reset signal RESET2 s is input.

Besides, as illustrated in FIG. 7, the column select circuit 1751includes switch transistors 26-1 to 26-4. The switch transistor 26-1includes switch transistors (cell transistors) 26-1 a, 26-1 b, 26-1 cand 26-1 d, each of which has a current path with one end connected tothe wiring line M1 a via a wiring line LI-9 and the other end connectedto a global source line GSL1 (M1) via a wiring line LI-10, and has agate electrode to which a control signal CGE1 s is input.

In addition, the switch transistor 26-2 includes switch transistors(cell transistors) 26-2 a, 26-2 b, 26-2 c and 26-2 d, each of which hasa current path with one end connected to the wiring line M1 b via awiring line LI-11 and the other end connected to the global source lineGSL1 (M1) via a wiring line LI-12, and has a gate electrode to which acontrol signal CGE2 s is input.

The switch transistor 26-3 includes switch transistors (celltransistors) 26-3 a, 26-3 b, 26-3 c and 26-3 d, each of which has acurrent path with one end connected to the wiring line M1 c via a wiringline LI-13 and the other end connected to the global source line GSL1(M1) via a wiring line LI-14, and has a gate electrode to which acontrol signal CGE3 s is input.

The switch transistor 26-4 includes switch transistors (celltransistors) 26-4 a, 26-4 b, 26-4 c and 26-4 d, each of which has acurrent path with one end connected to the wiring line M1 d via a wiringline LI-15 and the other end connected to the global source line GSL1(M1) via a wiring line LI-16, and has a gate electrode to which acontrol signal CGE4 s is input.

In the meantime, the wiring line Mia and global source line GSL1 (M1)are physically cut by the above-described M1cut step. Similarly, thewiring lines M1 b, M1 c and M1 d and the global source line GSL1 (M1)are physically cut by the above-described M1cut step.

In addition, the global source line GSL1 (M1) is connected to a globalsource line GSL1 (M2) via a via-contact V1.

In FIG. 7, in each of the switch transistors 26-1 to 26-4, fourtransistors are operated as one transistor. Alternatively, in each ofthe switch transistors 24-1 to 24-4, more than four transistors, forinstance, 8 transistors or 16 transistors, may be operated as onetransistor.

The wiring lines designated by “M1” are formed by the same fabricationstep, the wiring lines designated by “M2” are formed by the samefabrication step, and the wiring lines designated by “LI” are formed bythe same fabrication step. In addition, the plugs designated by “V1” areformed by the same fabrication step. Besides, the transistors 23 of thecell array 11, the reset transistors (cell transistors) 27, and theswitch transistors (cell transistors) 26-1 a, 26-1 b, 26-1 c, 26-1 d,26-2 a, 26-2 b, 26-2 c, 26-2 d, 26-3 a, 26-3 b, 26-3 c, 26-3 d, 26-4 a,26-4 b, 26-4 c, and 26-4 d are cell transistors of the same size.

Next, referring to FIG. 8 to FIG. 10, the layout of the column selectcircuit 17B1 is described. In FIG. 8, for the purpose of simpledescription, only eight local bit lines LBL and eight local source linesLSL are shown, and only eight word lines WL in the cell array 11 areshown. In addition, in FIG. 8 to FIG. 10, the direction of extension ofword lines WL (gate electrodes GC) is set to be a row direction (firstdirection), and a direction substantially perpendicular to the rowdirection is set to be a column direction (second direction). The bitlines BL and source lines SL extend in the column direction.

As illustrated in FIG. 8 to FIG. 10, in the cell array 11, column selectcircuit 17B1 and bit line discharge circuit 17B2, cell transistors 23,24, 25 are provided at intersections between gate electrodes GC andactive areas AA. Two cell transistors 23, 24, 25 are provided inassociation with one active area AA.

As illustrated in FIG. 8, the active areas AA of the cell array 11, bitline discharge circuit 17B2 and column select circuit 17B1 in the firstembodiment extend in a direction crossing the gate electrodes GC at apredetermined angle. Specifically, the active areas AA are inclined at apredetermined angle to the row direction. For example, the active areaAA in the first embodiment extends in a direction crossing the gateelectrode GC at an angle of (90−a tan (1/3)). Specifically, the activearea AA is inclined at an angle of about 71.565° to the row direction.

The configuration of the memory cell array 11 is disclosed in U.S.patent application Ser. No. 13/420,106 filed Mar. 14, 2012 and entitled“SEMICONDUCTOR STORAGE DEVICE”. The entire descriptions of these patentapplications are incorporated by reference herein.

In addition, in the first embodiment, the width of the gate electrode GC(word line WL) in the column direction, or the distance betweenneighboring gate electrodes GC (word lines WL), is 3/2 times or 2/3times as large as the width of the active area AA in the row direction,or the distance between neighboring active areas AA.

For example, the width of the gate electrode GC in the column direction,or the distance between neighboring gate electrodes GC, is about 34.8nm. The width of the active area AA or the distance between neighboringactive areas AA is about 21.923 nm. The active area AA is inclined at anangle of a tan (1/3) degree (about 18.435°) to the column direction.Accordingly, the width of the active area AA in the row direction or thedistance between neighboring active areas AA is about 23.2 nm. Thus, inthis case, the width of the gate electrode GC in the column direction,or the distance between neighboring gate electrodes GC, is 3/2 times aslarge as the width of the active area AA in the row direction or thedistance between neighboring active areas AA.

Since the pitch of the bit line BL and source line SL is in accordancewith 1.5 times as large as the pitch of the active area AA, the ratiobetween the pitch of the bit line EL and source line SL (column) and thepitch of the word lines WL (row) is 1:1. On the other hand, the ratiobetween the line & space of the active area AA and the line & space ofthe gate electrode GC (word line WL) is 2:3.

In this manner, by inclining, for example, the active area AA at anangle of (90−a tan (1/3)) from the row direction, and by setting theratio in pitch between the active area AA and gate electrode GC (wordline WL) at 2:3, the MTJ elements 22 may be arranged at equal intervals(equal pitch) in the column direction and row direction. In theabove-described concrete example, the interval between the MTJ elements22 neighboring in the column direction and row direction is about 69.6nm.

As illustrated in FIG. 8 and FIG. 9, in the cell array 11, the MTJelement 22 is provided on a via-contact V0, at a position between anupper electrode UE and the via contact V0. Two MTJ elements 22 areformed at both ends of the active area AA, and are connected to a commonsource region 100 a(S) via associated cell transistors 23. One MTJelement 22 and one cell transistor 23 constitute a memory cell MC.Specifically, the active areas AA are isolated in the direction ofextension thereof in units of two cell transistors 23 (memory cells MC),and two memory cells MC are provided in each active area AA.

As shown in FIG. 8 and FIG. 9, in the cell array 11, active areas AA anddevice isolation regions (Shallow Trench Isolation; STI) 104 arealternately formed on a semiconductor substrate 100. Cell transistors 23are formed in the active area AA. The cell transistor 23 includes a gateelectrode 102 (word line WL) which is buried in the semiconductorsubstrate 100, and includes a source region 100 a(S) and a drain region100 b(D) of an N+ type on both sides of the gate electrode 102. In themeantime, the gate electrode 102 is insulatively isolated from thesemiconductor substrate 100 by an insulation layer 101. In addition, thegate electrode 102 is insulatively isolated from the wiring line M1, M2by an insulation layer 103.

Two cell transistors 23 are formed in the same active area AA, and thesetwo cell transistors 23 share the source region 100 a(S) or drain region100 b(D). It is assumed that the two cell transistors 23 share thesource region 100 a(S).

The common source region 100 a(S) of the cell transistor 23 iselectrically connected to a first wiring line M1 which is formed of afirst metal wiring layer, via a contact plug 106(CB). The first wiringline M1 functions as a local source line LSL.

The drain region 100 b(D) of the cell transistor 23 is electricallyconnected to a lower end (e.g. a pin layer) of the MTJ element 22 viathe via-contact V0.

An upper end (e.g. a free layer) of the MTJ element 22 is connected tothe upper electrode UE. In the row direction, the upper ends of twomutually neighboring MTJ elements 22 are connected to the common upperelectrode UE, and the upper electrode UE is connected to a second wiringline M2 which is formed of a second metal wiring layer. The secondwiring line M2 functions as a local bit line LBL. An interlayerinsulation film (Inter-Layer Dielectric) ILD is provided for insulationbetween wiring lines.

In a data write or data read operation, in order to select a certainmemory cell MC, a gate electrode GC (word line WL) corresponding to thismemory cell MC is driven. Thereby, a plurality of cell transistors,which are connected to the word line WL and are arranged in the rowdirection, are rendered conductive. Then, by applying a voltage betweenthe bit line BL1 and source line SL1 of a certain column, a memory cellMC corresponding to an intersection between the selected word line WLand the selected bit line BL1 and source line SL1 is selected, and anelectric current can be caused to flow to the MTJ element of theselected memory cell MC via the cell transistor.

As illustrated in FIG. 8 and FIG. 10, in the column select circuit 17B1,active areas AA and device isolation regions (Shallow Trench Isolation:STI) 104 are alternately formed on the semiconductor substrate 100. Celltransistors 24 are formed in the active area AA. The cell transistor 24includes a gate electrode 102 (word line WL) which is buried in thesemiconductor substrate 100, and includes a source region 100 a(S) and adrain region 100 b(D) of an N+ type on both sides of the gate electrode102. In the meantime, the gate electrode 102 is insulatively isolatedfrom the semiconductor substrate 100 by an insulation layer 101. Inaddition, the gate electrode 102 is insulatively isolated from thewiring line M1, M2 by an insulation layer 103.

Two cell transistors 24 are formed in the same active area AA, and thesetwo cell transistors 24 share the source region 100 a(S) or drain region100 b(D). It is assumed that the two cell transistors 24 share thesource region 100 a(S).

The common source region 100 a(S) of the cell transistor 24 iselectrically connected to a wiring line LI via a via-contact VL1. Inaddition, the wiring line LI is electrically connected via a via-contactVL2, which is provided on the wiring line LI, to a first wiring line M1which is formed of a first metal wiring layer and functions as a globalbit line GBL.

The drain region 100 b(D) of the cell transistor 24 including a gateelectrode CGE2 is electrically connected to a wiring line LI via avia-contact VL1. In addition, the wiring line LI is electricallyconnected to a first wiring line M1 which is formed of a first metalwiring layer, via a via-contact VL2 provided on the wiring line LI. Thiswiring line M1 is electrically connected to the local bit line LBL2 viaa via-contact V1 which is provided between the cell array 11 and the bitline discharge circuit 1782.

The drain region 100 b(D) of the cell transistor 24 including a gateelectrode CGE3 is electrically connected to a wiring line LI via avia-contact VL1. In addition, the wiring line LI is electricallyconnected to a first wiring line M1 (not shown) which is formed of afirst metal wiring layer, via a via-contact VL2 (not shown) provided onthe wiring line LI. This wiring line M1 is electrically connected to thelocal bit line LBL3 via a via-contact V1 which is provided between thecell array 11 and the bit line discharge circuit 17B2. An interlayerinsulation film (Inter-Layer Dielectric) ILD is provided for insulationbetween wiring lines. Further, a wiring line M2 is provided above thewiring line M1, via the ILD. This wiring line M2 functions as a globalbit line GBL, and is electrically connected to the wiring line M1 (GBL)via the via-contact V1.

In the bit line discharge circuit 17B2, the cell transistor 25 has thesame structure as the cell transistor 23, 24. As described above, thecell transistors 23, 24 and 25 have the same structure and size.

Next, referring to FIG. 11, the layout of the column select circuit 1751and source line discharge circuit 17S2 is schematically described. InFIG. 11, for the purpose of simple description, only eight local bitlines LBL and eight local source lines LSL are shown, and only eightword lines WL in the cell array 11 are shown.

As illustrated in FIG. 11, the structures of the column select circuit1751 and source line discharge circuit 17S2 are the same as thestructures of the column select circuit 17B1 and bit line dischargecircuit 17B2 described with reference to FIG. 8. Thus, the celltransistor 23 of the cell array 11, the transistor 26 of the columnselect circuit 17B1 and the transistor 27 of the bit line dischargecircuit 17B2 have the same structure and size.

As has been described above, in the column select circuit 17B1, 1751,bit line discharge circuit 17B2 and source line discharge circuit 17S2in the first embodiment, the transistors 24 to 27 can be disposed withthe pitch of the word line WL in the cell array 11. However, deviceisolation is necessary between transistors neighboring in the columndirection, and one gate electrode needs to be set at a ground potential(GND) with respect to three gate electrodes. In FIG. 6 and FIG. 7, forthe purpose of simple description, the gate electrode (GND) is notshown.

<Manufacturing Method of the Semiconductor Storage Device According tothe First Embodiment>

Next, referring to FIG. 12, a basic manufacturing method of thesemiconductor storage device according to the first embodiment isschematically described. FIG. 12 is a flowchart which schematicallyillustrates the basic manufacturing method of the semiconductor storagedevice according to the first embodiment.

FIG. 12 illustrates, in a simultaneous manner, a manufacturing processof the cell array 11 and a manufacturing process of the column selectcircuit 17B1, 17S1, bit line discharge circuit 17B2 and source linedischarge circuit 1752. For the purpose of simple description, thecolumn select circuit 17B1, 1751 is simply referred to as “column selectcircuit”, and the bit line discharge circuit 17B2 and source linedischarge circuit 17S2 are simply referred to as “discharge circuit”.

[Step S1001] (Target Areas: Cell Array, Column Select Circuit, andDischarge Circuit)

A hard mask (not shown) is formed on the semiconductor substrate 100. Aresist (not shown) with a stripe shape of a line & space (L/S) patternis formed on the hard mask. Then, using the resist as a mask, the hardmask is processed, and the L/S pattern is transferred onto the surfaceof the semiconductor substrate 100 by using the processed hard mask.Subsequently, a process film (not shown) or a resist (not shown) iscoated on the semiconductor substrate 100.

[Step S1002] (Target Areas: Cell Array, Column Select Circuit, andDischarge Circuit)

A staggered pattern is formed on the resist, so as to cut the L/Spattern, which has been transferred on the semiconductor substrate 100,at predetermined intervals. Using the resist and the process film, theL/S pattern, which has been transferred on the semiconductor substrate100, is cut (AAcut) at predetermined intervals. Then, an insulation filmis buried in recesses in the semiconductor substrate 100. Thereby, thecut area becomes a shallow trench isolation STI. In the descriptionbelow, for the purpose of simple description, a projection formed on thesemiconductor substrate 100 is referred to as an active area AA.

[Step S1003] (Target Areas: Cell Array, Column Select Circuit, andDischarge Circuit)

A hard mask (not shown) is formed on the semiconductor substrate 100. Aresist (not shown) with a stripe shape of an L/S pattern is formed onthe hard mask. This L/S pattern extends in a direction crossing theactive area AA at a predetermined angle. Then, using the resist as amask, the hard mask is processed, and the L/S pattern is transferredonto the surface of the semiconductor substrate 100 by using theprocessed hard mask. Subsequently, insulation films 101, 103, 104 andgate electrodes 102 are formed in the L/S pattern.

[Step S1004] (Target Areas: Column Select Circuit, and DischargeCircuit)

Following the above, in the column select circuit and discharge circuit,via-contacts VL1 are formed on source and drain regions of the activearea AA.

[Step S1005] (Target Areas: Column Select Circuit, and DischargeCircuit)

Subsequently, in the column select circuit and discharge circuit, wiringlines LI are formed on the via-contacts VL1. By the wiring lines LI,plural cell transistors are electrically connected in parallel.

[Step S1006] (Target Areas: Column Select Circuit, and DischargeCircuit)

Then, in the column select circuit and discharge circuit, via-contactsVL2 are formed on the wiring lines LI.

[Step S1007] (Target Area: Cell Array)

Subsequently, in the cell array 11, a contact plug CB is formed on thesource region 100 a(S) of the semiconductor substrate 100.

[Step S1008] (Target Areas: Cell Array, Column Select Circuit, andDischarge Circuit)

Then, wiring lines M1 are formed on the via-contacts VL2 and contactplug CB.

[Step S1009] (Target Areas: Column Select Circuit, and DischargeCircuit)

Subsequently, those portions of the wiring lines M1, which need to bephysically cut, in the column select circuit and discharge circuit, arecut (M1cut).

[Step S1010] (Target Area: Cell Array)

Then, in the cell array, via-contacts V0 are formed on the drain regions100 b(D) of the semiconductor substrate 100.

[Step S1011] (Target Area: Cell Array)

Subsequently, in the cell array, MTJ elements 22 are formed on thevia-contacts V0.

[Step S1012] (Target Area: Cell Array)

Then, in the cell array, an upper electrode UE, which connects two MTJelements 22 is formed.

[Step S1013] (Target Areas: Column Select Circuit, and DischargeCircuit)

Next, in the column select circuit and discharge circuit, via-contactsV1 are formed on the wiring lines M1.

[Step S1014] (Target Areas: Cell Array, Column Select Circuit, andDischarge Circuit)

Subsequently, wiring lines M2 are formed on the via-contacts V1.

As has been described above, the manufacturing processes of the cellarray, column select circuit and discharge circuit are performed in asimultaneous manner in Steps S1001, S1002, S1003, S1008 and S1014.

<Advantageous Effects of the Semiconductor Storage Device According tothe First Embodiment>

According to the above-described first embodiment, the active areas AAin the cell array 11, column select circuit 17B1, 17S1, bit linedischarge circuit 17B2 and source line discharge circuit 17S2 cross thegate electrodes GC at a predetermined angle. In addition, the celltransistors in the cell array 11, column select circuit 17B1, 17S1, bitline discharge circuit 17E2 and source line discharge circuit 17S2 havesubstantially the same structure and size.

In this manner, the column select circuit 17B1, 17S1, bit line dischargecircuit 17B2 and source line discharge circuit 17S2 can be reduced insize by being laid out by using the cell rule of the cell array 11.

In addition, when use is made of the process in which the active areasAA and gate electrodes GC cross at a specific angle, the variance amongmemory cells can be suppressed and the manufacturing yield can beimproved.

Besides, since the same process can be used in the cell array 11, columnselect circuit 17B1, 1751, bit line discharge circuit 17B2 and sourceline discharge circuit 17S2, no load is added to manufacturingprocesses.

Second Embodiment

Next, a semiconductor storage device according to a second embodiment isdescribed. In the second embodiment, an additional description is givenof the structure of the subhole. In the second embodiment, thestructural elements having substantially the same functions andstructures as in the above-described first embodiment are denoted bylike reference signs, and an overlapping description is given only wherenecessary.

<Structure of a Semiconductor Storage Device According to a SecondEmbodiment>

Referring to FIG. 13 and FIG. 14A, FIG. 14B, FIG. 14C and FIG. 14D, thesemiconductor storage device according to the second embodiment isdescribed. FIG. 13 is a block diagram which schematically illustratesthe structure of the subhole, FIG. 14A is a circuit diagram illustratingan inverter of a column select circuit driver, FIG. 14B is a circuitdiagram illustrating an SWD driver of the column select circuit driver,FIG. 14C is a circuit diagram of the SWD driver, and FIG. 14D is acircuit diagram of a BL/SL reset driver.

As illustrated in FIG. 13, the subhole 16 includes an SWD driver 16 a, aBL/SL reset driver 16 b, and a column select circuit driver 16 c. Inaddition, the word line driver 20 includes SWD (sub-word line decoder)drivers 20 a and 20 b.

In addition, as illustrated in FIG. 13, FIG. 14A and FIG. 14B, thecolumn select circuit driver 16 c includes an inverter 30 and an SWDdriver 31. The inverter 30 includes a PMOSFET 30 a having a current pathwith one end supplied with VPP and the other end connected to a node N1,and having a gate to which a driving signal FYB is input; and an NMOSFET30 b having a current path with one end connected to the node N1 and theother end connected to a ground potential, and having a gate to whichthe driving signal FYB is input. A signal FY is output from the node N1.The column select circuit driver 16 c includes, for example, two suchinverters 30.

The SWD driver 31 includes a PMOSFET 31 having a current path with oneend to which the FY is input, and the other end connected to a node N2,and having a gate to which a select signal MLYB is input; an NMOSFET 31b having a current path with one end connected to the node N2 and theother end connected to a ground potential, and having a gate to whichthe select signal MLYB is input; and an NMOSFET 31 c having a currentpath with one end connected to the node N2 and the other end connectedto a ground potential, and having a gate to which the driving signal FYBis input. A signal SLY is output from the node N2. The column selectcircuit driver 16 c includes, for example, eight such SWD drivers 31.

In addition, as illustrated in FIG. 13 and FIG. 14C, the SWD driver 16 aincludes a PMOSFET 32 a having a current path with one end supplied withVPP and the other end connected to a node N3, and having a gate to whicha driving signal FXB is input; and an NMOSFET 32 b having a current pathwith one end connected to the node N3 and the other end connected to aground potential, and having a gate to which the driving signal FXB isinput. A signal FX is output from the node N3.

Furthermore, as illustrated in FIG. 13 and FIG. 14D, the BL/SL resetdriver 16 b includes a PMOSFET 33 a having a current path with one endsupplied with VPP and the other end connected to a node N4, and having agate to which a driving signal DIS is input; and an NMOSFET 33 b havinga current path with one end connected to the node N4 and the other endconnected to a ground potential, and having a gate to which the drivingsignal DIS is input. A signal DISB is output from the node N4.

Besides, as illustrated in FIG. 13, an inverter 32 is provided in aregion neighboring the subhole 16. The inverter 32 supplies signals FY(four signals) to the SWD driver 31 of the neighboring subhole 16.

<Advantageous Effects of the Semiconductor Storage Device According tothe Second Embodiment>

As illustrated in the above-described FIG. 13, the structures of the SWDdrivers 20 a and 20 b and SWD driver 31 are the same.

In addition, the signals, which are input to the respective circuits inthe subhole 16, are input via wiring lines M3 which are formed above thewiring lines M2.

By using the subhole 16 with the above-described structure, as shown inFIG. 13, the length of the bit line and source line controller 17 andthe length of the subhole 16 can be made substantially equal in thedirection of the bit line BL and source line SL.

Specifically, by laying out the SWD driver 31 of the subhole 16 inaccordance with the SWD drivers 20 a and 20 b, the subhole 16 can belaid out without a useless space at an intersection part between the SWDdrivers 20 a and 20 b and the bit line and source line controller 17.

In the meantime, in the above-described first embodiment, the activeareas AA are cut at predetermined intervals. However, the active areasAA may not be cut.

In addition, in the above-described first embodiment, the active areasAA are inclined at an angle of about 71.565° to the row direction, butthe embodiment is not limited to this example. For example, the activeareas AA may be configured to extend in a direction crossing the gateelectrodes GC at an angle of (90−a tan (1/2)). Alternatively, the activeareas AA may be configured to extend in a direction crossing the gateelectrodes GC at 45°.

In each of the above-described embodiments, the MRAM has been describedas the storage device by way of example. However, the embodiments canalso be implemented as other resistance change type memories includingthe same elements as illustrated in the first and second embodiment, forexample, as an element used in a PRAM or PCRAM (phase change randomaccess memory), or a ReRAM (resistive random access memory).

Besides, in each of the above-described embodiments, the bit line pairhas been referred to as the bit line BL and source line SL, forconvenience's sake. However, the embodiment is not limited to thisexample, and the bit line pair may be referred to, for example, as afirst bit line and a second bit line.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the methods andsystems described herein may be made without departing from the spiritof the inventions. The accompanying claims and their equivalents areintended to cover such forms or modifications as would fall within thescope and spirit of the inventions.

What is claimed is:
 1. A semiconductor storage device comprising: a cellarray including a plurality of resistance change elements formed above asemiconductor substrate, a plurality of first cell transistors formed onthe semiconductor substrate and provided in association with theresistance change elements, a plurality of first gate electrodesincluded in the first cell transistors and extending in a firstdirection, a first bit lines electrically connected to the resistancechange elements respectively and extending in a second directionperpendicular to the first direction, a second bit lines electricallyconnected to one end of a current path of the first cell transistorsrespectively and extending in the second direction, and a plurality offirst active areas in which the first cell transistors are formed, andwhich extend in a direction crossing the first direction at a firstangle; and a bit line controller including a plurality of second celltransistors formed on the semiconductor substrate and each having acurrent path with one end electrically connected to the first bit linesor the second bit lines, a plurality of second gate electrodes includedin the second cell transistors and extending in the first direction, anda plurality of second active areas in which the second cell transistorsare formed, and which extend in a direction crossing the first directionat a second angle.
 2. The semiconductor storage device of claim 1,further comprising a discharge circuit including: a plurality of thirdcell transistors formed on the semiconductor substrate, and each havinga current path with one end electrically connected to the first bitlines or the second bit lines, and with the other end electricallyconnected to a ground potential; a plurality of third gate electrodesincluded in the third cell transistors and extending in the firstdirection; and a plurality of third active areas in which the third celltransistors are formed, and which extend in a direction crossing thefirst direction at a third angle.
 3. The semiconductor storage device ofclaim 2, wherein the first cell transistors, the second cell transistorsand the third cell transistors have substantially the same size.
 4. Thesemiconductor storage device of claim 2, wherein the first angle, thesecond angle and the third angle are equal.
 5. The semiconductor storagedevice of claim 1, further comprising a first driver configured tocontrol the first gate electrodes are provided near an end portion ofthe cell array in the first direction.
 6. The semiconductor storagedevice of claim 5, further comprising a second driver configured tocontrol the second gate electrodes are provided near an end portion ofthe bit line controller in the first direction.
 7. The semiconductorstorage device of claim 6, wherein the second driver comprises the samecircuit as the first driver.
 8. The semiconductor storage device ofclaim 6, wherein a length of the bit line controller in the seconddirection is substantially equal to a length of the second driver in thesecond direction.
 9. The semiconductor storage device of claim 1,wherein a predetermined number of said second cell transistors havecurrent paths which are electrically connected in parallel, and havegate electrodes to which the same signal is input.
 10. The semiconductorstorage device of claim 1, wherein the bit line controller comprises afirst bit line controller configured to control a plurality of saidfirst bit lines, and a second bit line controller configured to controla plurality of said second bit lines.
 11. A semiconductor storage devicecomprising a cell array including: a plurality of resistance changeelements formed above a semiconductor substrate; a plurality of firstcell transistors formed on the semiconductor substrate and provided inassociation with the resistance change elements; a plurality of firstgate electrodes included in the first cell transistor and extending in afirst direction; a first bit lines electrically connected to theresistance change elements respectively and extending in a seconddirection perpendicular to the first direction; a second bit lineselectrically connected to one end of a current path of the first celltransistors respectively and extending in the second direction; and aplurality of first active areas in which the first cell transistors areformed, and which are provided under two resistance change elementssandwiching two said first gates which neighbor each other in the firstdirection.
 12. The semiconductor storage device of claim 11, furthercomprising a bit line controller including: a plurality of second celltransistors formed on the semiconductor substrate and each having acurrent path with one end electrically connected to the first bit linesor the second bit lines; a plurality of second gate electrodes includedin the second cell transistors and extending in the first direction; anda plurality of second active areas in which the second cell transistorsare formed, and which have the same shape as the first active areas. 13.The semiconductor storage device of claim 12, further comprising adischarge circuit including: a plurality of third cell transistorsformed on the semiconductor substrate, and each having a current pathwith one end electrically connected to the first bit lines or the secondbit lines, and with the other end electrically connected to a groundpotential; a plurality of third gate electrodes included in the thirdcell transistors and extending in the first direction; and a pluralityof third active areas in which the third cell transistors are formed,and which have the same shape as the first active areas.
 14. Thesemiconductor storage device of claim 13, wherein the first celltransistors, the second cell transistors and the third cell transistorshave substantially the same size.
 15. The semiconductor storage deviceof claim 13, further comprising a first driver configured to control thefirst gate electrodes are provided near an end portion of the cell arrayin the first direction.
 16. The semiconductor storage device of claim15, further comprising a second driver configured to control the secondgate electrodes are provided near an end portion of the bit linecontroller in the first direction.
 17. The semiconductor storage deviceof claim 16, wherein the second driver comprises the same circuit as thefirst driver.
 18. The semiconductor storage device of claim 16, whereina length of the bit line controller in the second direction issubstantially equal to a length of the second driver in the seconddirection.
 19. The semiconductor storage device of claim 12, wherein apredetermined number of said second cell transistors have current pathswhich are electrically connected in parallel, and have gate electrodesto which the same signal is input.
 20. The semiconductor storage deviceof claim 11, wherein the bit line controller comprises a first bit linecontroller configured to control a plurality of said first bit lines,and a second bit line controller configured to control a plurality ofsaid second bit lines.